Showerhead design

ABSTRACT

Embodiments described herein relate to a showerhead having a reflector plate with a gas injection insert for radially distributing gas. In one embodiment, a showerhead assembly includes a reflector plate and a gas injection insert. The reflector plate includes at least one gas injection port. The gas injection insert is disposed in the reflector plate, and includes a plurality of apertures. The gas injection insert also includes a baffle plate disposed in the gas injection insert, wherein the baffle plate also includes a plurality of apertures. A first plenum is formed between a first portion of the baffle plate and the reflector plate, and a second plenum is formed between a second portion of the baffle plate and the reflector plate. The plurality of apertures of the gas injection insert and the plurality of apertures of the baffle plate are not axially aligned.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/691,496, filed Apr. 20, 2015, which claims benefit of U.S.Provisional Application Ser. No. 61/994,584, filed May 16, 2014, whichare hereby incorporated by reference in their entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

Embodiments of the present disclosure generally relate to a showerheaddesign having a reflector plate with a gas injection insert for radiallydistributing gas.

Description of the Related Art

Semiconductor substrates are processed for a wide variety ofapplications, including the fabrication of integrated devices andmicrodevices. One method of processing substrates includes depositingoxygen radicals on an upper surface of the substrate. For example,Applied Materials, Inc., of Santa Clara, Calif., offers a RadOx® processthat heats the substrate with lamps and injects hydrogen and oxygen intoa processing chamber. The gases form radicals when they strike thesurface of the substrate to form a layer on the substrate, e.g., oxygenradicals form a silicon dioxide layer on a silicon substrate.

Current processing chamber showerheads used for radical oxygendeposition on 300 mm substrates have limited deposition control,resulting in poor processing uniformity. For example, low processingchamber pressure requirements for radial oxygen deposition and currentshowerhead designs result in gas reaching the substrate at a highvelocity. The high velocity of the gas causes impingement on thesubstrate and prevents the gas from being adequately heated. On theother hand, oxygen radicals generated from combustion quickly recombineto create a short life cycle for the oxygen radicals. Therefore, thelimited deposition control due to the high velocity of the gas combinedwith the short life cycle of oxygen radicals results in greaterdeposition at the center of the substrate, and poor deposition at theedges of the substrate.

Therefore, there is a need for an improved showerhead design thatprovides deposition control for more uniform deposition throughout thesubstrate, i.e., from the center to the edge.

SUMMARY OF THE DISCLOSURE

In one embodiment, a shower head assembly is disclosed herein. Theshowerhead assembly includes a reflector plate and a gas injectioninsert. The reflector plate has at least one gas injection port disposedtherethrough. The gas injection insert is disposed in the reflectorplate. The gas injection insert has a plurality of apertures. The gasinjection insert includes a baffle plate. The baffle plate is disposedin the gas injection insert. The baffle plate has a plurality ofapertures. A first plenum is formed between a first portion of thebaffle plate and the reflector plate. A second plenum is formed betweena second portion of the baffle plate and the reflector plate. Theplurality of apertures of the gas injection insert and the plurality ofapertures of the baffle plate are not axially aligned.

In another embodiment a processing chamber is disclosed herein. Theprocessing chamber includes a substrate support and a showerheadassembly. The substrate support is configured to rotate a substrateduring processing. The showerhead assembly is disposed above thesubstrate support. The showerhead assembly includes a reflector plateand a gas injection insert. The reflector plate has a first gasinjection port a second gas injection port disposed therethrough. Thegas injection insert is disposed in the reflector plate. The gasinjection insert has a plurality of apertures. The gas injection insertincludes at least two baffle plates radially disposed in the gasinjection insert about a center of the reflector plate. Each baffleplate has a plurality of apertures. A first plenum is formed between afirst portion of the baffle plate and the reflector plate. A secondplenum is formed between a second portion of the baffle plate and thereflector plate. The first plenum is separated from the second plenum bya wall of the reflector plate. The plurality of apertures of the gasinjection insert and the baffle plate are not axially aligned.

In yet another embodiment, a showerhead assembly is disclosed herein.The showerhead assembly includes a reflector plate and a gas injectioninsert. The reflector plate has a first injection port and a second gasinjection port disposed therethrough to deliver gas to a first plenumand a second plenum. The gas injection insert is disposed in thereflector plate, below the first and second plenums. The gas injectioninsert includes a plurality of apertures. The number and size of theapertures is selected based on the flow rate of gas flowing through thefirst and second gas injection ports. The gas injection insert includesa baffle plate disposed in the gas injection insert. The baffle plate isexposed to the first and second plenums. The baffle plate is configuredto reduce the flow of rate of gas flowing through the first and secondplenums.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a schematic view of a processing chamber according to oneembodiment of the disclosure.

FIG. 2A illustrates an enlarged view of a showerhead assembly, accordingto one embodiment of the disclosure.

FIG. 2B illustrates a cross-sectional enlarged view of a baffle platewith a gas injection insert disposed therein, according to oneembodiment of the disclosure.

FIG. 3 illustrates an enlarged bottom view of a reflector plateaccording to one embodiment of the disclosure.

FIG. 4 illustrates an enlarged top view of a gas injection insertaccording to one embodiment of the disclosure.

FIG. 5 illustrates an enlarged bottom view of a gas injection insertaccording to one embodiment of the disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

FIG. 1 illustrates a schematic view of a rapid thermal processingchamber 100 according to one embodiment of the disclosure. Althoughdetails of the disclosure are described as utilized within a rapidthermal processing chamber, embodiments described herein may be utilizedin other processing systems and devices where uniform deposition isdesired, such as other deposition chambers and etch chambers.

The processing chamber 100 includes a contactless or magneticallylevitated substrate support 104 and a chamber body 102. The chamber body102 has sidewalls 108, a bottom wall 110, and a top wall 112. Thesidewalls 108, bottom wall 110, and top wall 112 define an interiorvolume 121. The top wall 112 includes a lid 116 having a showerheadassembly 127. The sidewalls 108 typically include at least one substrateaccess port 148. The substrate access port 148 facilitates entry andegress of a substrate 140. The processing chamber 100 may also include aradiant heat source 106 disposed in an inside diameter of the substratesupport 104.

The substrate support 104 is adapted to magnetically levitate and rotatea substrate (not shown) within the interior volume 121. The substratesupport 104 includes an annular body 199. The annular body 199 includesa magnetic ring section 130 and a substrate support section 132. Thesupport section 132 extends from an upper surface of the magnetic ringsection 130 to support a support ring 134. The support ring 134facilities alignment and provides a seating surface for the substrate140.

The processing chamber 100 also includes a window 114 made from amaterial transparent to heat and light of various wavelengths. Thevarious wavelengths may include light in the infra-red (IR) spectrum,through which photons from a radiant heat source 106 may heat thesubstrate 140. The window 114 may also include a plurality of lift pins144. The lift pins 144 are adapted to selectively contact and supportthe substrate 140 to facilitate transfer of the substrate 140 into andout of the processing chamber 100.

In one embodiment, the radiant heat source 106 includes a lamp assemblyformed from a housing. The housing includes a plurality of honeycombtubes 160 in a coolant assembly 161. The honeycomb tubes 160 are coupledto a coolant source 183.

An atmosphere control system 164 is also coupled to the interior volume121 of the chamber body 102. The atmosphere control system 164 generallyincludes throttle valves and vacuum pumps for controlling chamberpressure.

The showerhead assembly 127 is configured to deliver one or more gasesto the substrate 140. The showerhead assembly 127 includes a reflectorplate 118 disposed below the lid 116. The reflector plate 118 faces thesubstrate support 104. The reflector plate 118 is configured to reflectIR light that is radiating off the substrate 140 back onto the substrate140. A cooling plate 115 may optionally be disposed around andcircumscribe the reflector plate 118 to cool the reflector plate 118.

In one embodiment, the showerhead assembly 127 includes at least a firstgas injection port 138 and a second gas injection port 128 formedthrough the lid 116 and the reflector plate 118. An enlarged schematicview of the first gas injection port 138 and the second gas injectionport 128 of the showerhead assembly 127 may be seen in FIG. 2A. Thefirst gas injection port 138 is configured to inject gas from a firstgas source 123 to a first plenum 129 in a generally radially inwarddirection. The second gas injection port 128 is configured to inject gasfrom a second gas source 125 to a second plenum 120 in a generallyradially inward direction. The first and second plenums 129, 120 areformed in the reflector plate 118. The first plenum 129 is exposed tothe first gas injection port 138. The second plenum 120 is exposed tothe second gas injection port 128.

In one embodiment, the first gas injection port 138 (for providing gasto the first plenum 129) is located in the second quarter of thereflector plate 118. For example, the first gas injection port 138 islocated between about 30 mm to about 40 mm from the center of thereflector plate 118. In one embodiment, the second gas injection port128 (for providing gas to the second plenum 120) is located in the firstquarter of the reflector plate 118. For example, the second gasinjection port 128 is located between about 112 mm to about 122 mm fromthe center of the reflector plate 118. In one embodiment, the first andsecond gas injection ports 138, 128 each have a diameter of betweenabout 1 mm and about 10 mm, for example, about 5 mm or about 5.1 mm.

In one embodiment, the first gas source 123 supplies oxygen gas (O₂) andthe second gas source 125 supplies hydrogen gas (H₂). An oxygen andhydrogen gas mixture (O₂/H₂) is thus supplied to the first and secondplenums 129, 120. In one embodiment, the gas mixture is between about 23percent to about 43 percent hydrogen gas, and between about 57 percentto about 77 percent oxygen gas, for example, about 33 percent hydrogengas and about 67 percent oxygen gas. The gas mixture flowing through thefirst plenum 129 forms an inner zone 171 in the showerhead assembly 127.The gas mixture flowing through the second plenum 120 forms an outerzone 172 in the showerhead assembly 127. The separate and distinct innerand outer zones 171, 172 in the showerhead assembly 127 advantageouslyallow the gas mixture to be controlled and tuned prior to beingdeposited on the substrate 140, depending on the processingrequirements.

The reflector plate 118 also includes one or more gas injection inserts124 disposed in the reflector plate 118. FIG. 3 illustrates an enlargedbottom view of the reflector plate 118. In one embodiment, the reflectorplate 118 includes one gas injection insert 124, two gas injectioninserts 124, each located about every 180 degrees around the reflectorplate 118 (as shown in FIG. 1), or four gas injection inserts 124,located about every 90 degrees around the reflector plate 118 (as shownin FIG. 3). The baffle plate 122 is coupled to the reflector plate 118by a plurality of screws 290. The plurality of screws are configured tofit within a plurality of screw holes 292 formed in the reflector plate118 and a plurality of screw holes 294 formed in the baffle plate 122.

FIG. 2B illustrates a cross-sectional view of a portion of the baffleplate 122 and the gas injection insert 124. The baffle plate 122 isshown coupled to an inner edge 202 of the gas injection insert 124. Forexample, in one embodiment, the baffle plate 122 may be welded to theinner edge 202 of the gas injection insert 124. The baffle plate 122 issuspended in the gas injection insert 124 such that the third plenum 131is formed between the baffle plate 122 and the gas injection insert 124.The apertures 117 in the baffle plate 122 are shown to be not be axiallyaligned with the apertures 126 formed in the gas injection insert 124such that a tortuous flow path is formed from the first and secondplenums (not shown) to the third plenum 131. FIG. 4 illustrates anenlarged top view of the gas injection insert 124. The gas injectioninsert 124 has a generally oblong shaped body. The gas injection insert124 includes an oblong shaped baffle plate 122 disposed in the body ofthe gas injection insert 124. The gas injection insert 124 includes aplurality of apertures 126 (shown in phantom in FIG. 4). The gasinjection insert 124 is configured to deliver the gas mixture from thefirst and second plenums 129, 120 through the apertures 126 into theinterior volume 121 and to the substrate 140. The baffle plate 122includes a plurality of apertures 117 formed therethrough. The baffleplate 122 is configured to deaden or slow the flow rate of the gasmixture flowing from the first and second plenums 129, 120 through theapertures 117 and evenly distribute the gas mixture to a third plenum131 defined by the baffle plate 122 and the injection insert 124.Beneficially, the baffle plate 122 also reduces the overall gas mixtureconsumption by about 30 percent. Experimental results indicate that thevelocity of the gas mixture may be reduced by about 98 percent. Forexample, the velocity of the gas mixture may be reduced from about 100m/s (using a conventional showerhead design) to about 10 m/s (using theabove described baffle plate 122) towards the substrate 140.

In one embodiment, the number of apertures 117 in the baffle plate 122is between about 20 and about 30 apertures 117, for example, about 24 orabout 25 apertures 117. In one embodiment, the apertures 117 are formedin a single column in the baffle plate 122. In one embodiment, theradius of the apertures 117 is between about 0.25 mm and about 1.52 mm,for example, about 0.793 mm. In one embodiment, the number of apertures126 in the gas injection insert 124 is greater than the number ofapertures 117 in the baffle plate 122.

In one embodiment, the apertures 126 in the gas injection insert 124 areformed in two columns. Each column may have between about 40 and about60 apertures, for example, about 40 apertures or about 50 apertures,i.e., about 100 apertures. Therefore, in one embodiment, there are about100 apertures 126 (50 apertures×two columns). In one embodiment, theapertures 117 and the apertures 126 are offset to create a tortuous flowpath through the showerhead assembly 127. In one embodiment, the radiusof the apertures 126 is between about 0.25 mm and about 1.52 mm, forexample, about 0.79 mm. In another embodiment, (i) the number and sizeof the apertures 126; (ii) the number of columns having the apertures126; and (iii) the thickness of the gas injection insert 124 itself, maybe selected based on the flow rate of the gas mixture flowing from thefirst and second plenums 129, 120 (i.e., the inner zone 171 and theouter zone 172) to the third plenum 131, and finally flowing radiallytowards the substrate 140.

FIG. 5 is an enlarged bottom view of a gas injection insert 500 having aplurality of apertures 126 varying in size. In one embodiment, theapertures 126 of the gas injection insert 500 vary in size to form a gasflow gradient. For example, the apertures 126 may have a larger surfacearea on one end of the gas injection insert 500 than an opposing end ofthe gas injection insert 500. In one embodiment, the apertures 126 areformed in two columns. Each column has about 50 apertures 126 (as shownin FIG. 5). The apertures 126 in each column increase gradually in sizefrom a first end 502 of the gas injection insert 500 to an opposingsecond end 504 of the gas injection insert 500. In one embodiment, theapertures 126 increase from a radius of between about 0.34 mm to about1.98 mm, for example, a radius of between about 0.44 mm to about 0.98mm.

Referring to FIGS. 1 and 5, the gas injection insert 500 is disposed inthe reflector plate 118, such that each column of about apertures 126,e.g., two columns having about 50 apertures 126 each, spans the lengthof both the first and second plenums 129, 120. As such, about a firsthalf of the apertures 126 in each column, i.e., about 25 apertures 126,span the length of the first plenum 129 as part of the inner zone 171.The second half of the apertures 126 in each column, i.e., about 25apertures 126, span the length of the second plenum 120 as part of theouter zone 172.

In one embodiment of operation, where deposition of the gas mixture maybe higher at the center of the substrate 140 than the edges of thesubstrate 140, two separate volumetric flow rates of the gas mixture maybe provided to the first and second gas injection ports 138, 128. Forexample, in one embodiment the overall gas mixture is provided at about2 s/m or about 5 s/m through the showerhead assembly 127.

In one embodiment, the gas mixture flowing through the first plenum 129has a slower flow rate than the gas mixture flowing through the secondplenum 120 in order reduce the center-high deposition on the substrate140. For example, the gas mixture is provided through the first gasinjection port 138 and into the first plenum 129 at about 0.69 slm orabout 1.71 slm (i.e., the inner zone 171). The gas mixture is thenprovided through the second gas injection port 128 and into the secondplenum 120 at about 1.31 slm or about 3.29 slm (i.e., the outer zone172). Because the first plenum 129 is disposed closer to the center ofthe substrate 140 that the second plenum 120, the first end 502 of thegas injection insert 500 (having the smaller aperture 126 size) isdisposed below the first plenum 129 to account for the center-highdeposition on the substrate 140. Conversely, because the second plenum120 is disposed closer to the edge of the substrate 140 than the firstplenum 129, the second end 504 of the gas injection insert 500 (havingthe larger aperture 126 size) is disposed below the second plenum 120.As such, the overall gas mixture flow rate through the showerheadassembly 127 can advantageously be individually controlled and tunedthrough the above disclosed inner and outer zones 171, 172 to create aneven gas mixture flow rate between the center and the edges of thesubstrate 140 and therefore promote overall uniform deposition over thesubstrate 140.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

1. A processing chamber comprising: a substrate support configured torotate a substrate during processing; and a showerhead assembly disposedabove the substrate support, wherein the showerhead assembly comprises:a reflector plate having a first gas injection port and a second gasinjection port disposed therethrough; and a gas injection insertdisposed in the reflector plate and having a plurality of apertures,wherein the gas injection insert comprises: at least two baffle platesradially disposed in the gas injection insert about a center of thereflector plate, each baffle plate having a plurality of apertures,wherein a first plenum is formed between a first portion of the baffleplate and the reflector plate, wherein a second plenum is formed betweena second portion of the baffle plate and the reflector plate, the firstplenum separated from the second plenum by a wall of the reflectorplate, and wherein the plurality of apertures of the gas injectioninsert and the baffle plate are not axially aligned.
 2. The processingchamber of claim 1, wherein the first plenum is concentric to the secondplenum.
 3. The processing chamber of claim 1, wherein the showerheadfurther comprises: a third plenum formed between the baffle plate andthe gas injection insert.
 4. The processing chamber of claim 3, whereinthe third plenum is in fluid communication with the first and secondplenums through the apertures formed through the baffle plate.
 5. Theprocessing chamber of claim 4, wherein the plurality of apertures of thegas injection insert are aligned in one or more columns.
 6. Theprocessing chamber of claim 5, wherein the plurality of apertures of thegas injection insert increase in diameter from a first end of the gasinjection insert to a second end of the gas injection insert.
 7. Aprocessing chamber, comprising: a substrate support configured to rotatea substrate during processing; and a showerhead assembly disposed abovethe substrate support, wherein the showerhead assembly comprises: areflector plate having a first gas injection port and a second gasinjection port disposed therethrough; a gas injection insert disposed inthe reflector plate and having a plurality of apertures; and at leasttwo baffle plates radially disposed in the gas injection insert about acenter of the reflector plate, each baffle plate having a plurality ofapertures, wherein a first plenum is defined between a first portion ofthe baffle plate and the reflector plate, wherein a second plenum isdefined between a second portion of the baffle plate and the reflectorplate, the first plenum separated from the second plenum by a wall ofthe reflector plate, wherein the apertures in the gas injection insertare not axially aligned with the apertures in the baffle plates, andwherein a gas mixing plenum is defined between the baffle plates and thegas injection insert, the gas mixing plenum in fluid communication withthe first plenum and the second plenum through the apertures in thebaffle plates.
 8. The processing chamber of claim 7, wherein the firstplenum is concentric with the second plenum.
 9. The processing chamberof claim 7, wherein the plurality of apertures in the gas injectioninsert is linearly arranged.
 10. The processing chamber of claim 8,wherein the diameter of the apertures of the gas injection insertincreases from a first end of the gas injection insert to a second endof the gas injection insert.